The present invention relates generally to high speed switching of high voltage, high current electrical pulses and more particularly to reliable fast switching of voltages and currents beyond the range of commercially available thyratrons such as for use in triggering high power ultraviolet lasers and in other applications.
Moderately high voltages and high currents can be switched rapidly and fairly reliably with conventional commercially available silicon-controlled rectifiers (SCRs), thyratrons and the like. To rapidly switch very high voltages a spark gap method is employed wherein a high voltage differential is applied between two relatively closely spaced electrodes causing a rapid switching spark to occur therebetween. The electrical action occurring is quite similar to the functioning of a spark plug in the engine of a conventional gasoline motor. The spacing of the electrodes is primarily a function of the voltage differential therebetween and the nature of the gas, air, or other intervening environment.
Problems are inherent in spark gap switches however. First the electrodes erode under continuous sparking and are relatively short-lived under heavy duty operation requiring frequent maintenance and replacement. Also, the spark timing is not precise leading to pulse jitter. Another problem that occurs with spark gap switches at high frequency or repetition rate operation is that the environment between the electrodes becomes in effect contaminated by the spark and requires a finite time to re-stabilize. To speed up reliable spark gap action a procedure has been developed whereby the gas or other interelectrode medium is flowed past the spark electrode to maintain a relatively constant pure medium between the electrodes at all times. At high spark rates, in and above the kilohertz range, the volume and rate of medium exhange flow becomes quite high and introduces an additional ancillary burden in the attempt to achieve a reliable stable high voltage, high current pulse.